1. Field of the Invention
The present invention relates to a treatment of a wrapped yarn coil wound on a bobbin end of a package formed by a yarn take-up machine, particularly to a method and apparatus for peeling off and removing a wrapped yarn coil of synthetic yarn for forming a transfer tail when a paper tube is used as a bobbin, and a conveyor line for effectively carrying out such operation.
2. Description of the Related Arts
Recently, when a synthetic yarn such as of polyamide fibers or polyester fibers is treated by a draw twister or a draw texturing machine, a transfer tail is formed on a bobbin of packages produced by a melt-spinning process, for connecting a trailing end of a preceding package with a beginning end of a subsequent package so that a continuous processing is possible. The transfer tail is formed at the initial stage of the package formation by winding a pig bunch (pig tail) on a bobbin end portion outside of a traverse range (see, for example, Japanese Examined Patent Publication No. 57-36233 and Unexamined Patent Publication No. 58-119553).
After the package is doffed from the take-up machine, the pig bunch is peeled off and a predetermined length of yarn is left on the bobbin end to form a true transfer tail. A free end of the transfer tail is fixed on the bobbin end by a tape, label or seal (see, for example, Japanese Unexamined Patent Publication Nos. 1-226668 and 1-321264).
In the prior art, such a pig bunch treating operation is manually carried out, and has drawbacks in that much man power and time are necessary, the products may be contaminated and the quality of the transfer tail may fluctuate.
To solve the above problems, there are many proposals for automating this process in that the pig bunch is scratched off by a scratch band provided on a robot, or peeled off in the peripheral direction of the bobbin after being melted by an electric heater, as disclosed in Japanese Unexamined Patent Publication Nos. 60-12570 and 2-43180.
However, these processes have been unsatisfactory.
Bobbins provided with a slit on a bobbin end for easily catching a yarn end have been widely used. Corresponding to the recent tendency to increase automatic yarn winders, the slit has a saw-tooth like configuration to enhance a yarn catching ability.
According to this type slit, since the yarn is fitted and caught into the saw-teeth, the yarn gripping force increases, for example, from 200 g to 1500 g. Therefore, the yarn portion caught by the slit is hard to remove manually or even mechanically. Even though the yarn body is removed, a broken end may be left in the slit and interfere with a package yarn when it is unwound from this package.
In addition, if the broken yarn end is left in a slit (even of a usual type), the yarn catching operation may fail when the bobbin is reused, due to the lowering of yarn gripping force.